1. Field of the Invention
The present invention relates to a motor, and more particularly, to the improvement of a motor that includes a motor casing made of a resin.
2. Description of the Related Art
An outdoor unit of an air conditioner includes a fan motor that drives a blower fan. A DC brushless motor having high efficiency has been employed as the fan motor due to a demand for energy saving in recent years. However, since vibration, which is caused by cogging torque, is generated in the DC brushless motor, there is a problem in that noise is generated from the outdoor unit.
A molded motor is known as a motor in which such vibration and noise can be suppressed. A stator of the molded motor is embedded in a motor casing by insert molding. For this reason, the molded motor is excellent in a damping property and a sound insulation property, and has a superior waterproof property. Accordingly, the molded motor is a versatile motor that can be used for not only an air conditioner but also various uses.
Further, a structure in which a damping member is disposed in a motor casing is known as a technique for improving the damping property and the sound insulation property of a fan motor (for example, Patent Document 1: JP-A-09-285068). In a fan motor 10 disclosed in Patent Document 1, an annular damping member 11 is provided on the outer periphery of a bearing portion 10a. The bearing portion 10a is supported by a holding portion 12a of a fan casing 12 with a damping member 11 interposed therebetween. For this reason, the vibration of the fan motor is absorbed by the damping member 11. Further, the generation of noise, which is caused by the transmission of the vibration to the fan casing 12, is prevented.
However, the damping member disclosed in Patent Document 1 rotates relative to a motor body due to vibration during the operation of the fan motor. As a result, the inner peripheral surface of the damping member wears out and the damping performance of the damping member deteriorates. Alternatively, there is a problem in that the position of the fan motor relative to the fan casing shifts.